Means for directing electromagnetic wave energy at a very low angle above the horizon

ABSTRACT

The present invention comprises substantially vertical electromagnetic radiators which are arranged to have the maximum current mode at the top of one or more radiators to direct the wave energy along the ground plane without radiating energy directly towards the sky, which are . . . as well known . . . reflected back to Earth to cause interference. The invention also includes means comprising a single or multiple wavelength vertical antenna whereby the second 90 electrical degrees of each 180 electrical degrees is shielded from radiation to avoid high angle radiation. While the aforesaid means provides wave concentration along the ground towards the horizon, additional arrangement of radiators are associated to concentrate this ground wave energy in less than 360* from the point of transmission as desired.

United States Patent 1 I i 1 3,761,940

Hollingsworth Sept. 25, 197 3 MEANS FOR DIRECTING 2,147,808 2/1939Alford 343/885 ELECTROMAGNETIC WAVE ENERGY AT A FOREIGN PATENTS ORAPPLICATIONS VERY LOW ANGLE ABOVE THE HORIZON 220,059 6/1942 Switzerland343/845 [76] Inventor: R. Lee Hollingsworth, 186 Secatogue Ln., West,West lslip, N.Y. 11795 [22] Filed: Dec. 10, 1969 [21] Appl. No.: 870,607

Related U.S. Application Data Continuation-impart of Ser. Nos 172,581,Feb. 12, 1962, Pat. No. 3,289,208, and Ser. No. 684,873, Nov. 21, 1967,abandoned.

521 user 343/826, 343/830, 343/890 511 rm.cr. H01q 21/00 58 FieldofSearch 343/825, 829, 830,

Primary Examiner-Eli Lieberman [57] ABSTRACT 846 tion to avoid highangle radiation. While the aforesaid means provides wave concentrationalong the ground [56], References Cited towards the horizon, additionalarrangement of radia- UNITED STATES PATENTS tors are associated toconcentrate this ground wave energy in less than 360 from the point oftransmission as 1,912,754 6/1933 Bohm et a1. 343/826 desired 2,195,2323/1940 Wells et a1. 343/826 2,417,793 3/1947 Wehner 343/826 2 Claims, 17Drawing Figures \M G eas/vr fi/Jre/5ur/0/t/ ffla 7?,4/1 S/y/I7ZZZ V V. 1I. I I, T/

Patented Sept. 25, 1973 3,761,940

4 Sheets-Sheet 2 F76; 6 v V Patented Sept. 25, 1973 4 Sheets-Sheet 5Z155 fiz z/A ish alery/ (8 414 Vi a/all Patented Sept. 25, 19733,761,940

4 Sheets-Shoat I IOc Fueum; FJGHT I HELD PATTERN PROVE!) FIELD OF HGA INVEN TOR.

MEANS FOR DIRECTING ELECTROMAGNETIC WAVE ENERGY AT A VERY LOW ANGLEABOVE THE HORIZON This is a continuation in part of my application Ser.No. 172,581, filed Feb. 12, 1962 from which U.S. Pat. No. 3,289,208issued, and application Ser. No. 684,873, filed Nov. 21, 1967, nowabandoned in favor of this continuation in part application.

The invention therefore includes means to concentrate along the Earth'ssurface most of the radiated energy from substantially a vertical typeantenna, and including the radiator types for use in the standard radiobroadcast band of frequencies from 5 35 to 1605 kilocycles, and theadjacent frequencies. Such radiators may be separated and distancedapart and phased to achieve field pattern directivity, yet radiatesubstantially no skywave energy according to the invention.

The basic principle of the invention and discovery may also be explainedby visualizing a fed concentric transmission line suspendedsubstantially vertical which has alternated quarter wave or 90 of theouter conductor cut away to allow radiation to take place during thefirst 50 percent of the time of each half wave of supplied wave energy,or a desired portion of the 180 length of each one half wave section.This reduces to a degree the apparent present standards of radiationefficiency, however the energy so radiated and received along the groundplane towards the horizon appears to have the same or higher efficiency.

To obtain the desired result in one embodiment of the invention, this isachieved by connecting one vertical 90 antenna at its top to anotherclose by vertical 90 antenna extending downward substantially toestablish ground level, both antennae being preferably lightly lumptuned at the feed end and at the far terminating end to providesubstantially equal high voltages at the feed end and at the terminatingend, with a half wave or 180 current distribution from the feed end upone quarter wave or 80 and down the next to the end or terminating end,comprising a partial radiating loop circuit wherein maximum current isat the top of the two one quarter wave sections. Such antenna can beomni-directional for transmission, but would be bidirectional forreceiving, due to the wave travel in space cutting both sections at ornear simultaneously to set up opposing currents, as in a radionavigation compass loop. Both the feed end and the downward extendingsection may be shielded by a concentric transmission line or othershielding means near the earth or termination to prevent radiation forabout the first of the radiators above real or established ground. Thisis desirable only to avoid excessive absorption at or near the groundlevel, and therefore reduce the energy instantly reflected from theearth near the installation. In the higher frequencies where theradiators are mounted many wavelengths above the earth, reflectionskyward from the earth is greatly reduced since radiation decreases bythe square of the distance from a nondirectional antenna. This inventiontherefore, in one embodiment resides in a sharply folded over antennaradiating means, comprising at least two one-quarter wave or 90antennae, which are fed to utilize the first half of the full energywave to cause the maximum of the current lobe to be full at the top orextreme high point of the radiating means. The current therefore ascendsto maximum as it passes through the substantially sharp pointed top toreturn to the ground terminating end, or the unterminated end of thesecond length while descending in current value towards the current zeromode. The metallic ground portion between the feed end and terminatingend is shaped to be noninductive in so far as possible, namely flat inconstruction. The current angle of direct radiation from the radiatorsnever effectively radiate but little above the horizon, and a currentdistribution effect is had that is the equivalent of, or perhaps betterthan, a flat topped vertical antenna, on which the flat top sectionwould be infinitely large in diameter. This is impossible to effectivelyobtain at lower operating frequencies, but this can be obtainedeffectively in the high frequency ranges of the spectrum. This statesthe basic invention and discovery rather precisely. A simplified versionof the invention for less efficiency, provides that a onequarter wave or90 antenna section be condensed within a shielding means such as a boxat the top of the tower, or placed in a concentric tower, and at least asecond one-quarter wave section be exposed and extended downwardvertically or at an angle as set forth hereinafter. Two or more downwardextended sections may be slanted and positioned to produce directivity,yet concentrate the energy toward the horizon.

The invention is therefore applicable for every application wheremaximum current is desired at or near the radiator tops or extremityfrom the point where radiation begins, in the applications of this newmethod of obtaining horizontally directive radiation. This is a new, andperhaps far reaching discovery, which will reduce tower heights;eleminate the need for tower base insulators, and reduce obstructiontower lighting requirements in some of the frequencies within thestandard broadcast band. With proper directivity in the horizontalplane, this type of radiation may allow thousands of radio frequenciesto be duplicated for local ground wave communications and broadcastuses, which may also be utilized for long distance intercontinentalcommunication purposes, when the frequencies used for localcommunication distances are carefully installed with proper safeguardsagainst skyward radiation, according to the present invention.

The invention provides new means for obtaining directional radiationusing only one tower support when the slanted or vertical one-quarterwave sections are arranged to provide desired field distortion ordirectivity of propogation within the limits available. To achieve theultimate in field pattern directivity two or more phased units arerequired, some of which may be parasitic radiator units. They may besupported by one tower, even on the low and intermediate frequencies.The invention is adaptable also for frequencies in the VHF and UHFbands, and in some of the lower microwave ranges of the electromagneticwave spectrum, and may be used in providing directive phased wave energyconcentrations of a high order, which greatly reduces weight and bulk,and in this respect, the ways of application are numerous, includinghigh speed mechanical scanning antennae. It is to be understood that inthe use of these antennae, the lower portion of the current lobe ispreferably shielded from radiation including its use in the standard andmedium frequency broadcast bands, therefore this lower portion of thelow angle radiated wave is also intended to be kept preferably at aminimum allowing radiation to take place below the maximum current lobepoint down to about thirty degrees above the feed or terminating end. Inutilizing the invention for microwave radiation escape apertures allowthe portions of the wave energy to escape in the plane substantiallyperpendicular to the direction of wave travel within a microwavegenerating cavity or from a wave guide through an aperture fromsubstantially the center of the current mode, thus allowing radiation totake place only in the direction desired. The cavity generator-radiatormay be suitably elevated.

The objects and purposes of the present invention become clear andunderstandable to those schooled in the art to which the inventionpertains, as the application is read and studied.

A detailed description of the invention follows the preleminarydescription with reference to the drawings wherein:

FIG. 1 shows the ground wave coverage and optimum angle of skywaveradiation according to the prior art, for a one-quarter wave verticalradiator or 90 antenna.

FIG. 2 shows the ground wave coverage and opti mum angle of skywaveradiation according to the prior art, for a one-half wave verticalradiator or 180 antenna.

FIG. 3 illustrates the ground wave pattern radiated from a one-quarterwave or 90 antenna according to the present invention.

FIG. 4 shows a preferred form of the invention for non-directionaltransmission, except in the horizontal plane around the system towardsthe horizon, for the most part.

FIG. 4b shows an antenna designed to give a distorted pattern.

FIG. 4C shows the pattern of the the FIG. 4b antenna.

FIG. 4d shows an alternative but less efiicient embodiment of theantenna.

FIG. 4e shows the directivity pattern of the FIG. 4d antenna.

FIGS. 4f and 4g show additional means to increase the directivity of thegeneric invention.

FIG. 5 shows an alternative form of the invention upon without the topshielding unit.

FIG. 6 shows a representative directive antenna according to the genericinvention.

FIG. 7 shows another version of the generic invention.

FIG. 8 shows an alternative means of suppressing the upper or outercurrent lobe of a directive antenna means according to the genericinvention.

FIG. 9 shows an alternative antenna according to the generic invention.

FIG. 9a shows novel antenna mounting means.

FIG. 10 shows further adaptation of the generic invention.

The generic aspects of the invention are found in all of the drawingsillustrated and described in the specification, namely means forproducing radiation from substantially a vertical radiator where thecurrent is maximum at the top of each radiator, or at the outer point ofradiation.

In describing my invention in detail, reference is first made to FIG.1.Similar parts are identified by the same numerals throughout thespecification and drawings. A one-quarter wave or 90 vertical radiatoris shown at 10. The current distribution is shown by the dotted curveindicated by I the term representing current. The ground system isindicated at 11. For directional use,

this ground system may have radiators above and below the earth. Forhigh frequencies, the antenna and established ground is metal, anddimensioned to be capable of being rotated or scanned as desired whenthe system is used in the VHF and UHF bands. The optimum angle ofradiation in FIG. I is shown by the arrow line 12, which represents theresultant angle of all of the directly radiated and ground reflectedsykwave energy components. This total number of radiated angledcomponents is almost infinite in number, each taking or being radiatedat separate and different angles. The graph showing the radiatedcharacteristics, and the extent of the effective ground wave coverage isshown at 13, and it is to be assumed that this represents a circleextending 360 around the vertical radiator 10.

FIG. 2 is identical to FIG. 1 except that radiator 10 is extended to aheight of one-half wavelength or 180 electrical degrees in length, withthe current distribution shown by the dotted curvature line representedalso by I. FIGS. 1 and 2 are presented to show the prior art in thefield.

FIG. 3 shows substantially the results obtained by the use of thepresent generic invention and discovery. It may be assumed that radiatorelements 10 and 10a in the various drawings may tend to show a slightbit of figure-eight type of directivity, however the radiators arelocated so close together that this directivity can be discounted intransmission, but would be present in a radio receiver if connected tothe antenna. Nondirective transmission along the ground plane wasconfirmed by proof of performance measurements. The current I curveshows that the current distribution is such as to avoid direct skywaveradiation from a slanted, or vertical radiator. The current curve I isthe equivalent of FIGS. 27b, Page 794 of Termans Engineering Handbook,(McGraw Hill), if the flat top section was enlarged sufficiently to foldthe current over at right angles a full one-quarter wavelength from thetop as shown partially by the Terman reference, except that the flat topsection would itself direct energy in many directions including Skyward.

FIG. 4 shows a preferred embodiment of the invention to providenon-directional transmission in the ground plane. (This embodiment oftheinvention is claimed in U.S. Pat. No. 3,289,208, and the descriptionis here repeated for descriptive information only). The current mayfirst ascend up the feed radiator 10, and continues to descend towardsthe ground in radiator 10a from the summit or top of the highest pointof radiation supported by tower 10b. Both antenna sections 10 and 10amay connect directly to the top of tower means 10b which may be groundedor ungrounded at ll, since the tower radiates little if any unlessresonated to the frequency of the applied radio frequency energy. Thecurrent distribution is indicated by the dotted lines represented by I.Radiators 10 and 10a represent a full one-half wave or 180 antenna inlength from the feed point 15 through the complex tuned fircuit composedof inductance 16 and tuning condenser 17, which may be substituted for afull one-half wave dimension in length. The tuning of inductance l6 andcondenser 17 were used in the first installation as a convenience ofresonant adjustments, and their values were rather small. It is to beappreciated that a portion of the effective height of antenna 10 and 10amay not be allowed to radiate due to the elements of the complex tuningcircuits being shielded, or concentrated in shielding near theestablished ground level particularly on the low and medium wave lengthswhere it is impractical to have a full one-quarter wavelength verticaltower supporting means. The invention therefore provides that theradiation pattern area from radiators l and 10a, and of FIGS. 4,5,6,7and 4f is substantially vertical, and fully representative of thegeneric concept of the invention. It is to be also appreciated that theleaning angle of antenna 10 and 10a causes the vertical radiated waveenergy to be projected horizontally, substantially from the bottom tothe top of the antenna. In operation, the energy flows alternately up tothe top of 10 and 10a during the first 90 of each supplied alternationor 180 of energy, and down the second 90 section to provideomni-directional radiation in the direction of the horizon in 360. Theaction is reversed in the system on the next one-half cycle of appliedenergy. It must be kept in mind, that the downward flow of currentthrough 10 and 10a is not a directional change of current through 10 and10a during the full one-half wave current, however the field doesreverse, and this field reversal is such as to regeneratively increasethe current in the opposite radiator. Since this regenerative effecttakes place within the time of 180 electrical degrees of time at theapplied frequency, it can be assumed that the radiation field is bulgedin the direction of the horizon.

FIG. 4b shows the arrangement of at least two angled radiators 10 and10a supported by 10b to provide distortion and directivity according toFIG. 4c. The low angle radiated energy towards earth 11 from radiatorsl0 and 10a is largely absorbed and re-radiated or reflected at a highangle as explained in the description of FIG. 4, whereas the radiationto the right of the radiator support in FIG. 40 indicates distortion ofthe radiation towards the horizon to the right of the tower 10b.

FIG. 4d illustrates another adaptation of the invention wherein thetransmitter 100 supplies energy by transmission line 10b and supportingmeans, to the concentrated and shielded first one-quarter wavelength ofthe one-half wave antenna, the second one-quarter wave section indicatedat 10a. The shield and support 10b and 10d is preferably connectedtogether and to ground 11, which is normally the transmitter cabinet.The current curve I which shows the current distribution in theradiating sections is indicated by the dotted line I to the right ofradiator 10a, and it is to be appreciated that this pattern extendsaround radiator 10a 360, and the radiated energy to the left of 10a isreduced in that it is largely directed towards the earth, resulting in adistorted field pattern as indicated in FIG. 4c with the field patternshown by the dotted line distorted to the right of radiator 10a. It isto be understood that the embodiment of the invention shown by FIGS. 4,4d,4f, 5 and 7 may be distanced apart and fed in such time and phaserelationship to produce substantially all field patterns obtainable bydistanced apart and phased insulated vertical radiators as used and wellknown in the prior art, however, all of the prior art installationsradiated the usual skywave energy as illustrated in FIGS. 1 and 2. It isto be understood that more 10a radiators may be connected to shield 10and differently angled downward to vary the directive pattern or toprovide non-directional radiation towards the horizon, and in thisadaptation of the invention, a substitute is had for an extremely largeand costly flat topped tower such that would be completely uneconomicaland would not provide the same good quality of anti-skywave features asprovided by FIG. 4d of the invention. Here then, the present inventioncomprises all means adaptable for exciting an antenna, and having onlythe second half or halves of the radiators downward from a point ofelevation above the earth to avoid skywave radiation by having thecurrent maximum at the top of each onequarter wave radiator.

FIG. 4f in conjunction with FIG. 43 illustrates that the geometrics ofthe invention can be utilized in a versatile manner to achieve suitabledirectivity to satisfy many needs and requirements in the field ofelectromagnetic field transmission, yet only one radio tower isrequired, and without radiating skywave energy. In FIG. 4f transmitterconnects to branched transmission line 19, which comprises a precisioncommon point feed, to supply electromagnetic wave energy to one-quarterwave radiators 10 and 10a to the right of tower 10b and exactly the sameinstant that the energy is fed to one-quarter waveradiators 10x and 10yon the opposite side of tower 10b in equal amounts of power. This hasthe effect of feeding two spaced apart one-half wave radiators inparallel, therefore the total currents flowing into both radiatorsections would be considerably increased because the radiationresistance would be substantially altered, and the field reactionsbetween all radiating elements is increased, therefore the fielddistortion or directivity is increased substantially as indicated by theestimated pattern of FIG. 4g which is derived from FIG. 4c, the patternof a proof of performance made on an installation representative of FIG.4b. It is to be understood that radiator 10 and 10y may be commonlyconnected to equalize the total field reactions. Radiators 10 and 10a ofFIG. 4b were separated 45 for the proof of performance pattern of FIG.40, therefore to produce the Figure-eight it can be assumed thatradiators 10x and 1032 are also separated 45. By varying the angle ofseparation of 10 and 10a, and 10x and 10y, it is possible to obtainalmost any pattern of directivity desired with one supporting tower bypositioning each pair of radiators at different positions relative toeach other around the tower. FIGS. 4d and 4f and all possible geometricvariations described or alluded to comprises means to fully accomplishthe generic purposes and accomplishments of the invention, namely, thatof operating with currents at the maximum heights of a plurality ofone-quarter wave radiators to provide concentration of wave energy alongthe earth toward the horizon without radiating little, if any, skywaveenergy.

FIG. 5 shows antenna elements 10 and 10a to be substantially vertical,and connected across the top of 10b supporting means, through anon-radiating shield means 18 which could take other forms such as abalanced five wire line. It is intended that shielding means 18 averagesup to 10 of a wavelength in the AM broadcast band (535 1605 kilocycles),to provide a reasonable separation between 10 and 10a. Radiators 10 and10a may be two insulated radio towers built close together with anon-radiating connecting means 18 connecting the tops of the towers sothat the dimension of the system invention may be met, but with a lightapparent loss due to the non-radiation through connection 18. Theoperation of this embodiment of the invention is substantially asdescribed in FIG. 4. Sections 10 and 10a may indeed be leaned inaccordance with FIG. 4 if desired so long as the connection 18 acrossthe top is present. In this adaptation of the generic invention, lessground reflected energy towards the sky is accomplished it the lower 30be shielded from radiation as illustrated.

FIG. 6 shows two elements of a directive antenna system which is excitedas heretofore described except that radiators and 10a are separated adesired distance apart and connected at the tops by a nonradiatingtransmission line 18, in such phase and distance of physical separationrelationship as to cause radiation to take place in time and inductiverelationship to produce directivity as desired utilizing the knownmethods and techniques that are applicable to produce directivity. Inthis embodiment of the generic invention two directional factors arepresent and involved, namely, the fact that each one-quarter waveradiator 10 and 10a have maximum current at their tops to avoidradiation skyward, so by the phasing of the radiators by separationgoverns the amount of energy directed in one or more directions towardthe horizon along the ground plane only, without skywave radiation inthe direct manner as in the prior art as shown and described in FIGS. 1and 2.

FIG. 7 shows another generic embodiment of the invention whereinradiator element 10 is fed with current and is shieldedbeyond themidpoint of the first current lobes maximum value, as illustrated by thecurrent distribution curve I shown at the right. The current fed fromterminal passes up through non-radiating line 18 and along throughshielded support means 19 via 10a finally reaching complex tuning means16 and 17, which may or may not be connected to ground. Also the outercircuit 19 may be excited through the tuning circuit means 16 and 17instead of through terminal 15; not radiate from 10a which is shorted(not shown) to 19 at the top of 19. Here unit 19 is tuned by 16a and 17ato cause the outside circuit to radiate according to the inventionnamely, that of having the radiating current maximum at the top of theradiator 19. It is a part of the invention, that 19 be all, or a part ofa supporting tower; be fed through complex tuning circuits l6 and 1?,assuming that 10, 10b and 18 are not present in the radiating system,therefore center conductor 10a and shield 19 are connected at the top(not shown) and used for a non-directional anti-skywave system havingmaximum current at the top of shield 19 in accordance with thegenerically related system invention.

For frequency modulation broadcast transmission and televisiontransmission, and other forms of communication in the VHF and UHF andadjacent frequency bands, the present invention may be more readilyadapted according to FIGS. 8,9 and 10, and other possible configurationsnot shown, where radiator 10 in part comprises the center conductorsattached to the transmission line. Shielding lengths 18a are spaced toshield the upper half of the one-half wave energy from radiating skywardwhen positioned vertically as in FIGS. 8 and 9 hereinafter described.

FIG. 8 shows a vertical, (or flat if horizontal) area view of aradiating system and supporting plate and pipe means through which thefeed lines pass from slip ring contacts 25 and 26 providing aconcentrated radiation that is generic to and in accordance with thepresent invention, because of concentric shield means 18a. Thetransmission line 24 is formed into a rigid support for the directivearray. Radiators 10 are cut to one-half wavelength of the frequency tobe used, however nonradiating concentric line shields or studs 23prevent a great deal of the low angle radiation up to approximately 30on each radiator from being radiated. The current that is radiated, isbetween the 30 point up to about the 100 point of each one-half cycle or180 of energy fed to provide directivity looking down the plane of thearray to the right. The remaining approximately of the one-half waveradiators 10 are shielded from radiation by concentric shielding means18a. The two transmission lines 24 connect to radiators 10 from the sliprings 25.Slip Rings 25 and brush connectors 26 are representative ofstationary electric feed connections when the antenna pipe supportingmeans 19 is not to be scanned. Scanning movement of the supporting means19 may be in any direction desired, as when scanning or searching inradar and navigation purposes. Arrow 27 is indicative of desiredscanning capability, both in Azimuth and elevation for directive systemsof FIGS. 8,9 and 10. The distance between the radiators l0 and the farend terminating resistance (not shown to right) determines the degreeand efficiency of directivity. Supporting means 20 may be rotated toprovide horizontal, or vertical polarization. A flat shield plate, notshown, may extend along and outward from pipe 20, 90 from either line orradiators 10, and this shield arrangement may be equally spaced betweenboth horizontal and vertical radiators along an array to facilitate bothvertical and horizontal component transmission, and to provide improvedmultiplexing, and diversity transmission effects with properly orientedreceiving antenna means. The current I distribution curve of FIG. 8indicates that the energy radiated from both sets of doublets orradiators 10, is not seriously off direction along the plane orprojection of the radiated waves. The transmission line 24 may betransposed as required to provide phase reversals along the line and tobalance out unwanted inductive effects. With the array of radiatorspositioned in the vertical plane as illustrated, the energy is notradiated skyward but is concentrated toward the horizon. With the arrayrotated 90 the energy is concentrated into a cheese slice-like wavepattern extended from a position on the horizon upwards into the skydepending on the sharpness of the beam of energy radiated. This providesa beam suitable for radar navigation scanning.

FIG. 9 shows a self supporting radiator 10 which comprises a rod memberusually several wavelengths long, that passes up through an outerconcentric shielding pipe means 18b. As support for this verticalantenna, and other types of small antenna, the bottom of pipe 18b isthreaded and screwed into fitting 28, which is welded tothe antennamounting means 29, and is made to fit the roof line of a house as wellas a flat roof or surface area, when mounting means 29 is made toconform to a flat surface. This mounting means 29 covers a substantialarea of the roof, and is fastened securely through the roof structure 30by large bolts or wood screws 31 and 32. Lock nut 33 locks the threadedfitting 28 making it water proof. Transmission line 34 connects to 10and to a radio receiver or transmitter in the building or mobile craft.This type of mounting is intended for use in place of the strapped tothe chimney" method of mounting and supporting television antennae,commercial communication antennae and citizen band communicationsystems. Antenna mounting means 19 may be made as a hinge means to fitthe straight line of any roof as shown in FIG. 9a, or of a flat roof, orof any elevated mounting area. It may be a plate formed to fit eachrooftop or area on which it is to be mounted. In FIG. 9a pipe 28 iswelded around an opening to pass transmission line 34 through or arounda ball-like fitting or clamping means 35 and into pipe means 18b.Locking nut and bolt means 36 extending through the clamping means 35,locks and holds 18b in a vertical position as adjusted. Before lockinghowever, 18b is adjusted to provide the correct orientation of theantenna for best directive transmission or reception. If a motorizedrotor mechanism is to be used the base of 18b is secured, and the motorgear control unit is mounted above the roof or mounting elevation inseries with supporting pipe means 18b. Hinge fastening means 37 isstrong; is made of the lightest metal having good strength, and wheremaximum strength is required, the hinge or plate means is made of strongdurable dipped steel plating. The roof installation is water proofed inthe usual manner with suitable sealing compounds when necessary. Theplate supporting means may be other than a solid plate or hinge means.It may be a squared-up steel frams means with a relatively small areaalong the roof line, but fastened to cover a rather wide area of theroof so that hook means 38 can be attached to receive hooks on aservicemans ladder, and to attach guy wires to give further support to18b when higher than usual antenna elevations are required. Here the guywires are fastened to the metal plate or frame and are not connected toa number of places on the roof as in the case of normally guyedinstallations which causes roof damage. On the larger installations onbuilding tops, this is a major factor, and the mounting means made andconstructed, and installed according to the present invention precludessuch roof damage, and eliminates the possibility of falling parts.

In describing the antenna of FIG. 9, shields 18a are substantiallyone-quarter wavelength long. Iflower portion of the current I from zeroto 30 is not to be radiated, then shields 18a may be slightly longerthan onequarter wavelength, which reduces the one-quarter wave area forradiation from sections at the bottom of each 90 radiating section,however the one-half wave dimension indicated to the right in thedrawing remains the same. In the prior art, shields 18a have beenvariously used for matching uses (impedance matching), or to allow theescape of a full one-half wave or radiation, however applicant has neverbeen able to find a record of where these adjustments have been made toshield the radiation in a manner to effectively eliminate the upper halfportion of each one-half wave of radiation, and when vertically erectedavoid radiation directly towards the sky. In the prior art it apparentlyhas been assumed that the upper portion of the radiating element, thatis, the upper portion of each one-half wavelength are required toradiate for full efficiency. Specific directivity within the 360 ofhorizon, when desired, is provided by reflector means 18d which isattached to pipe 18b. This reflector 18d may be scanned around theantenna to produce a rotating beam as in radar and navigation systems.For this use, shields 18a may be removed to allow the usual skywaveradiation to take place. Presently known and used high gain multiplewave stacked antenna all radiate strong skywave energy angled well abovethe horizon as indicated by serious intermittent interference in the VHFand UHF frequency bands. The generic ambodiment of FIG. 9 reducesskywave transmission to a minimum.

In FIG. 10 the two wire transmission line 24 connects with radiators l0and 10a which have the slant angle effect of FIG. 4. The currentdistribution for each radiating unit in the array, is indicated by theupper and lower cirrent I curves. Stub shields, or short concentricouter conductors 23 are projected from pipe 20 and prevent radiation inthe lower portion of the total onehalf wave area comprised ofapproximately the first 30 and the last 30 of radiators l0 and 10a,leaving the remaining of the total of energy to radiate almost wholly inthe plane parallel to the pipe surface 20. When transmission line 24 isstrong and rigid and capable of self support, it may be scanned for theuses heretofore set forth in the description of FIG. 8. When theantennae described herein are used for shipboard use, they may bestabilized in known ways.

The present invention can be used to improve television, high speedfacsimile, computer signalling and tele-printer transmission, to reduceshort time echoes to the elements of received signals. This type ofshort time echo interference is disasterous to color televisionreception in cities such as New York and other large cities where shorttime signal delays due to reflections from buildings and airplanes,particularly when the color signals are transmitted and receivedaccording to NTSC standards using the shadow masked tubes with threebeams. Where the single beam color transmission and reception is used,utilizing the raster grid control means in the reproducing tubes, thecondition is greatly improved in that some delayed signal elements arelocked out from being reproduced. The fact that very serious reflectionsoccur from airplanes several thousand feet in the sky speaks loudly forthe need for more concentration of transmitted energy in the horizontalplane parallel to the earths surface, discounting the earths curvatureup to 20-30 miles from the point of transmission.

There is also great need for increased directivity in high gaincommunication and radar antennae on the lower radar frequencies, withoutexcessive bulkiness, weight and wind resistance. The present inventionmeets these requirements at least in part.

It is impossible to prevent all radiated energy from being reflectedback from the ionosphere and/or the troposphere, however when theelectromagnetic waves travel as substantially surface waves leaving thetransmitting antenna, the great distance they must travel to and fromthe point of reflection, determines to a large degree the strength thesignals are received back on earth far removed from the point oftransmission, consequently they are weak or undetectable, except forsporadic bursts of multi-reflections which by chance concentratesimultaneously on the far distant receiving antenna.

The various illustrated versions within this application point to thesingle generic aspect of the invention, namely, antenna radiating meansconnected, arranged and utilized to avoid high angle radiation above thehorizon from the point of transmission, and converged into less than 360around the point of transmission.

I claim:

1. In the field of electromagnetic wave radiation, a wave antenna havinga physical length of substantially one-half wavelength at the resonantoperating fre-- quency and connectable to a source of electromagneticwave energy to be radiated into space, said antenna extending upwardlyat an angle from the vertical to a supimum current at their tops toavoid radiating energy except in the vicinity of the horizon.

2. An antenna according to claim 1, wherein the radiation is the productof phased energies from two or more pairs of radiators to produce wavepropogation along the ground plane and concentrated at least in onedirection and substantially at the horizon area.

1. In the field of electromagnetic wave radiation, a wave antenna havinga physical length of substantially one-half wavelength at the resonantoperating frequency and connectable to a source of electromagnetic waveenergy to be radiated into space, said antenna extending upwardly at anangle from the vertical to a supporting means with respect to theexisting ground one-quarter wavelength, then extended downwardlyonequarter wavelength, said two one-quarter wavelength sectionsseparated at ground level less than 180-degrees of a circle with thesupporting means within the circle to increase the field strength of theelectromagnetic wave transmission within the area encompassed by thesaid less than 180-degrees, each of said onequarter wavelength sectionof said antenna having maximum current at their tops to avoid radiatingenergy except in the vicinity of the horizon.
 2. An antenna according toclaim 1, wherein the radiation is the product of phased energies fromtwo or more pairs of radiators to produce wave propogation along theground plane and concentrated at least in one direction andsubstantially at the horizon area.